Here’s a very useful FAQ about backup withholding from the IRS. I wrote about backup withholding in relation to improper W-9 filing here.

What is a Taxpayer Identification Number (TIN)?

A TIN is one of the following four numbers.

A Social Security Number (SSN)

An Employer Identification Number (EIN)

An IRS individual taxpayer identification number (ITIN). Aliens who do not have an SSN, and are not eligible to get one should get an ITIN. Form W-7, Application for IRS Individual Taxpayer Identification Number, is used to apply for an ITIN.

An Adoption Taxpayer Identification Number (ATIN). An ATIN is a temporary tax identification number issued for a child born in the U.S. An ATIN is used as an identifying number is the child is not eligible for an SSN.

When is a TIN considered missing or incorrect?

Missing TIN – We consider a TIN to be missing if it is not provided. We also consider a TIN to be missing if it has more or less than nine numbers or it has an alpha character as one of the nine numbers.
Example: Missing SSN: 123-45-678
Example: Missing SSN: 123-45-67899
Example: Missing EIN: 12- 345678P

Incorrect TIN – We consider a TIN to be incorrect if it is in the proper format but the name/TIN combination doesn’t match or can’t be found on IRS or SSA files.
Examples of Proper Format:
Correct SSN: 123-45-6789
Correct EIN: 12-3456789[Read more…]